(Vb+Vr)2 = 26 km
Eq1: 2Vb + 2Vr = 26
(Vb-Vr)6 = 26 km
Eq2: 6Vb - 6Vr = 26
Add Eq1 and Eq2:
2Vb + 2Vr = 26
6Vb - 6Vr = 26
Multiply Eq1 by 3:
6Vb + 6Vr = 78
6Vb - 6Vr = 26
Sum: 12Vb = 104
Vb = 8.6667 km/h = Velocity of the boat.
In Eq1, replace Vb with 8.6667:
2*8.6667 + 2Vr = 26
2Vr = 26-17.3333 = 8.6666 km/h.
Vr = 4.3333 m/s = Velocity of the river.
A boat takes 2.0hr {\rm hr} to travel 26km {\rm km} down a river, then 6.0hr {\rm hr} to return.
1 answer
1 answer